Cranial anchoring and positioning system and method

ABSTRACT

A cranial anchor system configured to attach to an opening in a cranium includes an anchor member. The anchor member has a middle anchor portion and a lower anchor portion coupled to and disposed in a downward direction relative to the middle anchor portion. The lower anchor portion has a plurality of contact members, each of which have a leg that extends at least partially in the downward direction, a tab connected to the leg, and a rib disposed between the leg and the tab. The system further includes an outer sheath and an inner sheath disposed within the outer sheath and slidable relative to the outer sheath.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a '371 National Stage Entry of PCT application No. PCT/US18/23065, which claims the benefit of U.S. Provisional Application No. 62/476,157 filed Mar. 24, 2017, both of which are incorporated by reference herein in their entireties.

TECHNICAL FIELD

A system and method for affixing an anchoring system to a cranium and accessing structures within the brain prior to and as part of a medical or surgical procedure is shown and described.

BACKGROUND

During a medical procedure it is desired to precisely and securely position and support a medical device in a fixed location relative to the patient. For example, during medical procedures that require access to the cranial cavity an external anchoring system is affixed to the skull. This anchoring system creates a fixed point of reference relative to the patient, thereby allowing for a higher degree of control and precision during a medical procedure. In addition, the anchoring system allows the medical device to access a location within a patient while maintaining operational control external to the patient. The anchoring system is attached to the skull by fasteners and includes a channel that accesses a bore in the skull. The channel can accommodate instruments such as a surgical probe or endoscope.

Existing cranial anchoring systems are secured to the skull by conventional methods such as the use of bone screws. While providing secure anchoring to the cranium is important, it is less than optimal to inflict any more trauma than is necessary to the skull during a procedure. For example, U.S. Pat. No. 8,845,655 describes a guide instrument that is placed over a burr hole in a patient's skull to enable operation on the patient's brain. Screws are employed to secure the base plate to the skull of a patient. The guide instrument requires multiple bone fixation screws to be placed in the patient's skull. This assembly increases the time it takes to position and attach the instrument and to remove the instrument from the patient. As a result, the patient's skull not only has a burr hole drilled therein, but must receive additional trauma from threaded bone fixation screws.

SUMMARY

An improved cranial anchoring system is disclosed. In one aspect of the disclosure, a cranial anchor system configured to attach to an opening in a cranium includes an anchor member that is elongated along a first axis. The anchor member includes a middle anchor portion defining a middle anchor recess that extends about the first axis and a lower anchor portion coupled to and disposed in a downward direction relative to the middle anchor portion along the first axis. The lower anchor portion includes a plurality of contact members that together define a lower anchor recess. Each of the plurality of contact members has a leg that extends from a bottom of the middle anchor portion, each leg having an angular bend defining an upper and a lower section of the leg, and a rib mounted to the leg. The system further includes an outer sheath that is elongated along a second axis and defines a first channel, the outer sheath including a joint configured to be at least partially disposed within the middle anchor recess and the lower anchor recess such that the joint is rotatable within the middle anchor recess and the lower anchor recess. The system also includes an inner sheath disposed within the first channel and slidable relative to the outer sheath along the second axis. The inner sheath defines a second channel that is elongated along the second axis.

In another aspect of the disclosure, a cranial anchor apparatus is configured to attach to an opening in a cranium. The anchor apparatus is elongated along a first axis. The apparatus includes a middle anchor portion that defines a middle anchor recess that extends about the first axis. The apparatus also includes a lower anchor portion coupled to and disposed in a downward direction relative to the middle anchor portion along the first axis. The lower anchor portion includes a plurality of contact members that together define a lower anchor recess. Each of the plurality of contact members have a leg that extends from a bottom of the middle anchor portion, the leg having an angular bend defining an upper and a lower section of the leg, and a rib mounted to the leg.

In yet another aspect of the disclosure, a cranial anchor apparatus is configured to attach to an opening in a cranium. The anchor apparatus is elongated along a first axis. The apparatus includes a middle anchor portion defining a middle anchor recess that extends about the first axis. The apparatus also includes a lower anchor portion coupled to and disposed in a downward direction relative to the middle anchor portion along the first axis. The lower anchor portion includes a plurality of contact members that together define a lower anchor recess. Each of the plurality of contact members has a leg that extends from the bottom of the middle anchor portion, each leg having an angular bend defining an upper and a lower section of the leg, and a rib mounted to the leg. The apparatus further includes a support ring connected to the middle anchor portion and disposed about the first axis and below at least a portion of each of the plurality of contact members.

Another aspect of the present disclosure is directed to methods of using the system and apparatuses described herein, including steps of positioning a cranial anchoring system onto a patient's skull.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional side view of a cranial anchoring system, according to an aspect of the present disclosure.

FIG. 2 is a perspective view of a cranial anchoring apparatus, according to an aspect of the present disclosure.

FIG. 3 is a side view of a cranial anchoring system, according to another aspect of the present disclosure.

FIG. 4A is a perspective view of a cranial anchoring apparatus, according to another aspect of the present disclosure.

FIG. 4B is a side view of the cranial anchoring apparatus illustrated in FIG. 4A.

FIG. 4C is a top view of the cranial anchoring apparatus illustrated in FIG. 4A.

FIG. 5A is an exploded isometric view of a locking assembly, according to an aspect of the present disclosure.

FIG. 5B is a side view of the locking assembly illustrated in FIG. 5A.

FIG. 6 is a cross sectional view of the anchor member with the locking assembly and the outer sheath secured thereto.

FIG. 7 is a perspective view of a cranial anchoring system, according to another aspect of the present disclosure.

FIG. 8 is a perspective view of a lower portion of the cranial anchoring system illustrated in FIG. 7, according to an aspect of this disclosure.

FIG. 9 is a cross sectional view of the cranial anchoring system illustrated in FIG. 7, according to an aspect of this disclosure.

FIG. 10 is a perspective view of the cranial anchoring system illustrated in FIG. 7 with a portion of a locking assembly positioned within, according to another aspect of this disclosure.

FIG. 11. is a side view of the cranial anchoring system illustrated in FIG. 10 with a locking assembly positioned within, according to another aspect of this disclosure.

FIGS. 12A-12C illustrate positions of a lower portion of the cranial anchoring system illustrated in FIG. 7.

DETAILED DESCRIPTION

FIG. 1 shows a side view of a cross section of a cranial anchoring system 100 such as the type used in a surgical procedure for removing intracranial fluid and tissue. As shown in FIG. 1, the system includes a reference array 112 similar to reference arrays used by existing surgical navigation systems such as, but not limited to, the Medtronic StealthStation™, Brainlab Curve™, or Stryker Nav3i™. In this view, an exemplary cranial anchoring system 100 is shown that can be positioned within a burr hole H of a skull S.

The cranial anchoring system 100 includes an anchor member or base plate 200, an outer sheath 104, an inner sheath 106, a height adjustment device 108, a locking member 110, and the reference array 112. The reference array 112 is operatively mounted onto the anchor member 200 to provide a reference point for the position of the anchoring system 100 on the skull S of a patient. Other components may be included within the system 100, for example, to provide additional support, to increase maneuverability, or to provide other functionality to facilitate the removal of intracranial fluid and tissue.

The anchor member 200 is configured to attach to the burr hole H of the skull S as will be described in greater detail below. The anchor member 200 provides a platform for the anchoring system 100 to be mounted to the skull S allowing for access and interface with the inside of the skull S.

Referring to FIG. 2, the anchor member 200 includes an upper anchor portion 202, a middle anchor portion 204, and a lower anchor portion 206. The upper anchor portion 202, the middle anchor portion 204, and the lower anchor portion 206 are axially aligned along longitudinal axis 50, such that the upper anchor portion 202 is above the middle anchor portion 204, and the middle anchor portion 204 is above the lower anchor portion 206. The terms “above” and “below,” as used herein, describe the positions of certain components relative to one another and are thus approximations. The terms “above”, “upper”, or “uppermost” mean a position that is closer to an uppermost portion of the cranial anchoring system 100, such as the inner sheath 106, and the terms “below”, “bottom”, or “bottommost” mean a position closer to a bottommost portion of the cranial anchoring system 100, such as the lower anchor portion 206 of the anchor member 200.

The middle anchor portion 204 includes an inner edge 205, a first surface 217, and a second surface 207 spaced from the first surface in an axial direction Al. The axial direction Al extends along the longitudinal axis 50. The inner edge 205 extends circumferentially about the longitudinal axis 50, thereby partially defining a middle anchor recess 209 within the middle anchor portion 204. The inner edge 205 of the middle anchor portion 204 defines a hole that may be circular in shape.

The lower anchor portion 206 extends downward from the second surface 207 of the middle anchor portion 204. The lower anchor portion 206 includes a plurality of contact members 208 that together define a lower anchor recess 201, each of which have a leg 203 that extends at least partially in the axial direction Al. Each contact member 208 has an inner contact surface 210, an outer contact surface 212, a rib 214, and a tab 216. Each rib 214 extends between the leg 203 and the tab 216 and is attached to the outer contact surface 212, and each tab 216 is attached to the bottommost end of the leg 203. Each rib 214 and each tab 216 extend at least partially outwardly relative to axis 50 in a radial direction R1. The radial direction R1 is perpendicular to the axis 50. Each tab 216 may be angled up relative to the radial direction R1 towards an uppermost part of the lower anchor portion 206 so as to form an acute angle relative to the respective contact member 208. Alternatively, tab 216 may be angled down relative to the radial direction R1 towards a bottommost part of the lower anchor portion 206 so as to form an obtuse angle relative to the respective contact member 208. Alternatively still, tab 216 may extend along, or substantially along the radial direction R1 so as to form a 90° degree angle relative to the axis 50. In some aspects, lower anchor portion 206 may include tabs that extend up, down, along radial direction R1, or any combination thereof. In some aspects, each rib 214 may be attached to the outer contact surface 212 without being attached to each corresponding tab 216. In some aspects, each contact member 208 may include a different configuration relative to the other contact members 208.

Multiple configurations of contact members 208 having ribs 214 and tabs 216 attached thereto may be incorporated into the lower anchor portion 206. For example, the lower anchor portion 206 may include any number of contact members 208, such as 12 contact members, so long as the contact members sufficiently attach the anchor member 200 to the skull S. In further examples, lower anchor portion 206 may include 8, 9, 10, 11, 13, 14, 15, or 16 contact members. Further, each contact member 208 may have a different configuration. For example, each contact member 208 may only include either a rib 214 or a tab 216. Alternatively, each contact member 208 may include both a rib 214 and a tab 216, or include neither a rib 214 nor a tab 216.

The contact members 208 may be outwardly biased, e.g. cantilevered, spring-loaded, or otherwise resiliently biased, such that when compressed radially inwardly, a force is exerted by the contact members 208 in the outwardly radial direction R1. For example, when the anchor member 200 is positioned within the burr hole H, the contact members 208 may exert a retention force on the edge of the burr hole H on the skull S and on the inner surface of the burr hole H in the skull S proximate to the burr hole H.

In some aspects of the disclosure, the ribs 214 may include a sharp edge 215. The sharp edge 215 may be configured to lightly penetrate a margin of the skull S when the anchor member 200 is positioned within the hole H. Sharp edge 215 functions to minimize or prevent movement of the anchor member 200 during the surgical procedure. Tabs 216 may also hook under the skull S to minimize or prevent outward migration of the anchor member 200. Anchor member 200 can be inserted into hole H by pushing in the axial direction A1 while rotating about axis 50.

Referring to FIGS. 1 and 2, the upper anchor portion 202 extends from the first surface of the middle anchor portion 204, and extends circumferentially about the longitudinal axis 50. An inner surface 211 of the upper anchor portion 202 defines a threaded region, such as an internally threaded region, and an upper anchor opening 213. The upper anchor opening 213 aligns with the middle anchor recess 209 of the middle anchor portion 204 along axis 50. An anchor outer surface 219 of the upper anchor portion 202 may define grooves, gear teeth, or the like, configured to allow the anchor member 200 to be gripped or otherwise manipulated.

The outer sheath 104 includes a joint 104 a and an upper outer sheath portion 104 b. The joint 104 a is positioned within the middle anchor recess 209 of the middle anchor portion 204. The joint 104 a is at least partially rotatably coupled to the inner contact surfaces 210 of the contact members 208, such that the outer sheath 104 rotates within the anchor member 200. The joint 104 a defines a lower sheath channel that extends along a sheath longitudinal axis 60. The sheath longitudinal axis 60 extends from a bottommost end of the outer sheath 104 to an uppermost end of the inner sheath 106.

The joint 104 a is spherical in shape. The positioning of the joint 104 a within the middle anchor portion 204 will act as a fulcrum for movement of the joint 104 a. For example, the movement of the joint 104 a within the middle anchor portion 204 may be similar to a ball and socket joint, such that the joint 104 a is restricted from movement in the axial direction A2 and the radial direction R2, but is free to move circumferentially.

The upper outer sheath portion 104 b is positioned above the joint 104 a along the sheath longitudinal axis 60. The upper outer sheath portion 104 b defines an upper sheath channel. The upper sheath channel aligns with the lower sheath channel along a sheath axial direction A2. The sheath axial direction A2 extends along the longitudinal axis 60. The movement of the joint 104 a relative to the anchor member 200 is minimized by contact between the joint 104 a and the locking member 110. In some aspects of the disclosure, the joint 104 a rotates up to 30 degrees relative to axis 50, such that the sheath longitudinal axis 60 is 30 degrees offset from the anchor longitudinal axis 50.

The inner sheath 106 is slidably disposed within the lower sheath channel and the upper sheath channel of the outer sheath 104. The inner sheath 106 defines an inner sheath channel that extends through the inner sheath 106 in the sheath axial direction A2. The inner sheath 106 extends through the anchor member 200 to provide access to the inside the skull S. Inner sheath 106 may be configured to extend inside the skull S a distance that provides access to target locations within the skull S.

In some aspects of the present disclosure, a conduit 107 may be coupled to a lower end of the inner sheath 106. The conduit 107 defines a conduit channel that aligns with the inner sheath channel. The conduit channel may have the same diameter as the inner sheath channel, or the conduit channel may have a diameter that is greater or smaller than the diameter of the inner sheath channel. The conduit channel may be disposed about axis 60 or it may be offset from axis 60. The conduit channel extends from the inner sheath channel to provide for greater access within the skull S.

The height adjustment device 108 is operationally coupled to the inner sheath 106, and rotatably coupled to the outer sheath 104. Rotation of the height adjustment device 108 about the sheath longitudinal axis 60 allows movement of the inner sheath 106 in the sheath axial direction A2. The height adjustment device 108 is rotatably coupled to the upper outer sheath portion 104b. For example, height adjustment device 108 may be fixed to the outer sheath 104 and include a threaded inner surface that mates with a threaded outer surface of the inner sheath 106, such that rotation of the height adjustment device 108 about the axis 60 moves the inner sheath 106 relative to the outer sheath 104 along the axis 60.

The locking member 110 defines a threaded region 114, such as an externally threaded region, and an internal locking surface 116. The region 114 of the locking member 110 is configured to mate with the threaded region of the inner surface 211 of the upper anchor portion 202, such that rotational movement of the locking member 110 about the longitudinal axis 50 secures the locking member 110 onto the anchor member 200.

The internal locking surface 116 of the locking member 110 is configured to engage the joint 104 a of the outer sheath 104. Contact between the internal locking surface 116 and the outer sheath 104 restricts or minimizes movement of the outer sheath 104 relative to the anchor member 200. For example, this contact restricts axial, radial, and circumferential movement relative to axis 50 of the outer sheath 104 within the anchor member 200. The restriction in movement is caused by friction between the internal locking surface 116 and the outer sheath 104, grooves or teeth positioned on the internal locking surface 116 and/or outer sheath 104, or other structural features that may be incorporated to limit movement.

The cranial anchoring system 100 may further include a pump 503, such as an aspiration or suction pump. The pump 503 may be coupled to an upper end of the inner sheath 106 via a flexible tube 505. The pump 503 may be peristaltic or continuous in nature, producing a suction force to draw intracranial fluid, tissue, or other intracranial matter, through the inner sheath 106 to an exterior of the skull S.

The cranial anchoring system 100 may also include a vibratory or ultrasonic mechanism (not shown). The vibratory mechanism may be coupled to an uppermost end of the anchoring system 100 and provide a vibratory or ultrasonic force to the inner sheath 106. The provided force assists in breaking up the fluid and tissue within the skull S, thereby minimizing the size of the particles to extract.

The cranial anchoring system 100 may further include an obturator (such as obturator 313 described below). The obturator may be slideably disposed within the inner sheath channel and extend out of the lowermost end of the inner sheath 106. The obturator may be configured to minimize or prevent unwanted coring of brain tissue during initial insertion of the inner sheath 106 within the skull S.

FIGS. 3 through 6 illustrate an alternate embodiment of a cranial anchoring system. Portions of the embodiment disclosed in FIGS. 3 through 6 are similar to aspects described above in FIGS. 1 and 2 and those portions function similarly to those described above. Cranial anchoring system 300 includes an anchor member or base plate 400, an outer sheath 304, an inner sheath 306, a height adjustment device 308, a locking assembly 310, and a reference array 312. The cranial anchoring system 300 may be positioned within the burr hole H of the skull S in a substantially similar manner as cranial anchoring system 100.

In some aspects of the disclosure, the system 300 may include a second reference array 315, shown in FIG. 3, slidably mounted within the inner sheath 306 or, alternatively, operatively mounted to the obturator. In other aspects of the disclosure, anchoring system 300 may include only a single reference array 315 attached to inner sheath 306, or alternatively, to the obturator. The arrays 312, 315 provide spatial reference information to a surgical navigation system (not shown). The navigation system locates the spatial reference point of the arrays 312,315 to determine the positioning of the inner sheath 306 relative to patient anatomy. The arrays 312, 315 can be configured to work with a variety of navigational systems that are known and used in the art. The navigation system may also receive information related to magnetic resonance imaging (MRI), computed tomography (CT), ultrasound imaging, or other image data set of the inside of the skull S. The navigation system provides real time information that allows the surgeon to precisely adjust the cranial anchoring system 300 to target a location within the patient.

The outer sheath 304, the inner sheath 306, the height adjustment device 308, the locking assembly 310, and the reference array 312 may be configured and aligned substantially similarly as the outer sheath 104, the inner sheath 106, the height adjustment device 108, the locking member 110, and the reference array 112 of the cranial anchoring system 100. Cranial anchoring system 300 may further include a spacer member 311 positioned between the locking assembly 310 and the outer sheath 304, such that the bottommost end of the locking assembly 310 interfaces with a lower end of the outer sheath via the spacer member 311.

The cranial anchoring system 300 may further include an obturator 313. The obturator 313 may be slidably disposed within the inner sheath channel defined by the outer sheath 304 and the inner sheath 306. The obturator 313 may extend out of the lowermost end of the inner sheath 306. Obturator 313 may be incorporated into cranial anchoring system 100 in a similar manner. The obturator 313 may also interface with a special reference array.

Referring to FIGS. 4A and 4B, the anchor member 400 includes an upper anchor portion 402, a middle anchor portion 404, and a lower anchor portion 406. The upper anchor portion 402, the middle anchor portion 404, and the lower anchor portion 406 are axially aligned along longitudinal axis 70, such that the upper anchor portion 402 is above the middle anchor portion 404, and the middle portion 404 is above the lower anchor portion 406. The upper anchor portion 402 and the middle anchor portion 404 may have a substantially similar structure to the upper anchor portion 202 and the middle anchor portion 204 of cranial anchoring system 100.

The lower anchor portion 406 extends from the middle anchor portion 404 and includes a plurality of contact members or feet 408 and a support ring 420. Each of the contact members 408 may include either or both of a rib 414 and a tab 416, and may include multiple configurations as described above with respect to contact members 208 of cranial anchoring system 100.

The support ring 420 extends at least partially in an axial direction A3 and circumferentially about longitudinal axis 70. The axial direction A3 extends along the longitudinal axis 70. A plurality of support arms 422 extend upwards from support ring 420. Each support arm 422 is spaced circumferentially about the longitudinal axis 70 and positioned in between the contact members 408. Each support arm 422 is coupled to the lower ring portion 424.

The lower ring portion 424 is positioned at a bottommost end of the support arms 422 in the axial direction A3. The lower ring portion 424 may align with the bottommost end of the contact members 408. In other aspects of this disclosure, the lower ring portion 424 may be positioned above or below (See FIG. 4B) the bottommost end of the contact members 408 in the axial direction A3.

The lower anchor portion 406 also includes a plurality of anchor ribs 430 that extend outwardly in a radial direction R3 along the lower anchor portion 406 from the uppermost end to the bottommost end. The radial direction R3 is substantially perpendicular to the axial direction A3. In an aspect of this disclosure, each of the anchor ribs 430 extend along each of the support arms 422 so as to strengthen support arms 422.

The outer sheath 304 is configured to be positioned within the middle anchor portion 404 and supported by the lower anchor portion 406 of the anchor member 400. More specifically, the outer sheath 304 may be supported by the contact members 408, the support arms 422, the lower ring portion 424, or combinations thereof

Referring to FIG. 4C, which illustrates a top view of the anchor member 400, the lower anchor portion 406 further includes a plurality of protrusions 432 that extend in the radial direction R3 from an inner anchor surface 434. The protrusions 432 may be spaced circumferentially about the lower anchor portion 406 and may be positioned in between each of the contact members 408.

FIGS. 5A and 5B illustrate an exploded perspective view and side view of the locking assembly 310, respectively, according to an aspect of this disclosure. The locking assembly 310 includes a threaded top 502 and a slotted bottom 504. The threaded top 502 defines a threaded region 506, such as an externally threaded region. The threaded region 506 is configured to mate with a threaded region 436, such as an internally threaded region (See FIG. 4C) of the upper anchor portion 402 so as to secure the locking assembly 310 to the anchor member 400.

The slotted bottom 504 is configured to extend at least partially into the lower anchor portion 406 of the anchor member 400 in the axial direction A3. The slotted bottom 504 may include a lower locking surface 508 and an outer surface 510. The lower locking surface 508 may engage and provide a downward force relative to axis 50 to the outer sheath 304, which bears on the lower ring portion 424 and pushes the contact members 408 outwardly in the radial direction R3, thereby further securing the outer sheath 304 within the anchor member 400. In this way, slotted bottom 504 functions similarly to spacer member 311 in that both interface between the locking members and the outer sheath. In an aspect of this disclosure, the slotted bottom 504 may be conical shaped, or otherwise shaped to maximize the contact between the lower locking surface 508 and the outer sheath 304 when the slotted bottom 504 is positioned within the anchor member 400.

The outer surface 510 of the slotted bottom 504 may define a plurality of slots 512 spaced circumferentially around the slotted bottom 504. Each of the slots 512 may be positioned to align with a corresponding protrusion 432 of the lower anchor portion 406. The alignment of each slot 512 with each protrusion 432 minimizes or prevents circumferential movement of the slotted bottom 504 relative to the anchor member 400.

FIG. 6 illustrates a cross sectional view of the anchor member 400 with the locking assembly 310 and the outer sheath 304 secured thereto, according to an aspect of this disclosure. The lower locking surface 508 is positioned at a bottommost end of the slotted bottom 504 and is configured to contact the outer sheath 304. The contact between the lower locking surface 508 and the outer sheath 304 may restrict or otherwise limit axial, radial, and circumferential movement of the outer sheath 304 when the outer sheath 304 is positioned within the anchor member 400. Further, while the locking assembly 502 is being secured to the anchor member 400, movement of the slotted bottom 504 relative to the outer sheath 304 may be substantially limited to axial movement due to the alignment of each slot 512 of the slotted bottom 504 with each protrusion 432 of the anchor member 400. Limiting movement between the split bottom 504 and the outer sheath 304 minimizes any disruption the slotted bottom 504 may have to the position, including the rotational position, of the outer sheath 304 while the outer sheath 304 is being secured to the anchor member 400.

FIGS. 7 through 12 illustrate an alternate embodiment of a cranial anchoring system. Portions of the embodiment disclosed in FIGS. 7A through 11 are similar to aspects described above in FIGS. 1 through 6 and those portions function similarly to those described above. Cranial anchoring system 600 includes an anchor member or base plate 700, an outer sheath 604, an inner sheath (not shown), a locking nut 608, a locking assembly 610, and a reference array (not shown). The cranial anchoring system 600 may be positioned within the burr hole H of the skull S in a substantially similar manner as the cranial anchoring systems 100 and 300.

The outer sheath 604, the inner sheath, and the reference array may be configured and aligned substantially similarly as the outer sheaths 104 and 304, the inner sheaths 106 and 306, and the reference arrays 112 and 312 of the cranial anchoring systems 100 and 300. The locking nut 608 may be configured to lock the inner sheath within the outer sheath 604, preventing axial movement between them. The cranial anchoring system 600 may also include an obturator (not shown) configured and aligned substantially similarly as the obturator 313 of cranial anchoring system 300.

Referring to FIGS. 8 and 9, the anchor member 700 includes an upper anchor portion 702, a middle anchor portion 704, and a lower anchor portion 706. The upper anchor portion 402, the middle anchor portion 404, and the lower anchor portion 406 are axially aligned along longitudinal axis 80, such that the upper anchor portion 702 is above the middle anchor portion 704, and the middle portion 704 is above the lower anchor portion 706. The upper anchor portion 702 and the middle anchor portion 704 may have a substantially similar structure to the upper anchor portions 202 and 402 and the middle anchor portions 204 and 404 of cranial anchoring systems 100 and 400.

The lower anchor portion 706 extends from the middle anchor portion 704 and includes a plurality of contact members 708 and a support ring 720. Each of the contact members 708 may include a leg 703 and a rib 714. The leg 703 and the rib 714 may include multiple configurations as described above with respect to contact members 208 and 408 of cranial anchoring systems 100 and 400. The support ring 720 may be configured and aligned substantially similarly to the support ring 420 of the cranial anchoring system 400.

Each leg 703 has an angular bend 705 that defines an upper section 713 of the leg 703 and a lower section 716 of the leg 703. The lower section 716 of the leg 703 extends from the angular bend 705 to an end 719 of the leg 703. The end 719 may define a bottommost end of each of the plurality of contact members 708 in an axial or downward direction A4. The axial direction A4 extends along the longitudinal axis 80. The lower section 716 includes a lower surface 717, which may comprise a planar configuration. In an aspect, an angle Φ formed at the angular bend 705 between the lower section 716 and the upper section 713 of the leg 703 may form an obtuse angle.

Each rib 714 may include a sharp edge 715 that extends along a length of each rib 714. Each rib 714 may be mounted on either the upper section 713 or the lower section 716 of the leg 703, or both the upper section 713 and the lower section 716. Each rib mounted on the lower section 716 of the leg 703 may extend from the angular bend 705 towards the end 719 of the leg 703. Each sharp edge 715 may extend parallel to the lower surface 717. Each rib 714 mounted on the upper section 713 may extend from the angular bend 705 toward the middle anchor portion 704.

The plurality of contact members 708 may be spaced circumferentially about the longitudinal axis 80. Each rib 714 may be mounted on the upper section 713 of the leg 703 or the lower section 716 of the leg 703. In an aspect, each consecutive pair of the plurality of contact members 708 includes a rib 714 mounted on the upper section 713 of the leg 703 and a rib 714 on the lower section 716 of the leg 703. For example, the ribs 714 may alternate between being mounted on the upper section 713 and the lower section 716 for every contact member 708 spaced about the lower anchor portion 706.

Referring to FIG. 9, the lower anchor portion 706 further includes a plurality of protrusions 732 that extend in a radial direction R4 from an inner anchor surface 734. The radial direction R4 is substantially perpendicular to the axial direction A4. The protrusions 732 may be spaced circumferentially about the lower anchor portion 706 and may be positioned in between each of the contact members 708.

The locking assembly 610 includes a threaded top 802 and a slotted bottom 804. The split top 802 defines a threaded region 806, such as an externally threaded region. The threaded region 806 is configured to mate with a threaded region 736, such as an internally threaded region of the upper anchor portion 702 so as to secure the locking assembly 610 to the anchor member 700.

The slotted bottom 804 is configured to extend at least partially into the lower anchor portion 706 of the anchor member 700 in the axial direction A4. The slotted bottom 804 may include a lower locking surface 808 and an outer surface 810. The lower locking surface 808 causes the outer sheath 604 to move in the A4 direction, which results in the outer sheath 604 forcing the contact members 708 outwardly in the radial direction R4. After the contact members 708 have been sufficiently deflected in the radial direction R4, the outer sheath 604 bears on the support ring 720, thereby further securing the outer sheath 604 between the lower locking surface 808 and the support ring 720. In an aspect of this disclosure, the slotted bottom 804 may be conical shaped, or otherwise shaped to maximize the contact between the lower locking surface 808 and the outer sheath 604 when the split bottom 804 is positioned within the anchor member 700.

FIGS. 10 and 11 illustrate the anchor member 700 with the slotted bottom 804 positioned within, according to aspects of this disclosure. The slotted bottom 804 is transparent in FIG. 10 and the anchor member 700 is transparent in FIG. 11 for illustrative purposes. The outer surface 810 of the split bottom 804 may define a plurality of slots 812 spaced circumferentially around the split bottom 804. Each of the slots 812 may be positioned to align with a corresponding protrusion 732 of the lower anchor portion 706. The alignment of each slot 712 with each protrusion 732 minimizes or prevents circumferential movement of the split bottom 804 relative to the anchor member 700.

The lower locking surface 808 is positioned at a bottommost end of the slotted bottom 804 and is configured to contact the outer sheath 604. The contact between the lower locking surface 808 and the outer sheath 604 may restrict or otherwise limit axial, radial, and circumferential movement of the outer sheath 604 when the outer sheath 604 is positioned within the anchor member 700. Further, while the locking assembly 702 is being secured to the anchor member 700, movement of the split bottom 804 relative to the outer sheath 604 may be substantially limited to axial movement due to the alignment of each slot 812 of the slotted bottom 804 with each protrusion 732 of the anchor member 700. The locking assembly 610 may be sized such that each protrusion 732 is received within each slot 812 prior to the threaded region 806 of the split top 802 being mated with the threaded region 736 of the upper anchor portion 702, thereby preventing the locking assembly 610 from being screwed together with the anchor member 700 while they are misaligned. In an aspect, the split bottom 804 may extend from the lower anchor portion 706 to the upper anchor portion 702 of the anchor member 700 when each protrusion 732 is positioned within each slot 812. Limiting movement between the slotted bottom 804 and the outer sheath 604 minimizes any disruption the split bottom 804 may have to the position, including the rotational position, of the outer sheath 604 while the outer sheath 604 is being secured to the anchor member 600.

The plurality of contact members 708 are configured to be actuated from an initial position, to a first position, and to a second position. FIG. 12A illustrates the initial position of the plurality of contact members 708. In the initial position, the contact members 708 are biased in the radial direction R4 prior to entering the burr hole H or otherwise not in use.

FIG. 12B illustrates the first position of the contact members 708 as they enter the burr hole H. In the first position, each contact member 708 extends inward in the radial direction R4 such that each lower surface 717 extends substantially parallel to a wall of the burr hole H. The sharp edge 715 of each rib 714 may contact the wall of the burr hole H. It will be appreciated that as the contact members 708 enter the burr hole H in the axial direction A4, the contact members 708 are compressed inward the radial direction R4.

FIG. 12C illustrates the second position of the contact members 708. In the second position, each contact member 708 extends outward in the radial direction R4 causing each lower surface 717 to extend at least partially in the radial direction R4. Each of the sharp edges 715 of each rib 714 apply pressure to the wall or edge of the burr hole H and may extend outward into the wall or edge of the burr hole H securing the anchor member 700 to the skull S.

The contact members 708 may be actuated between the first and second positions by the outer sheath 604. A lower outer sheath portion or joint 604 a of the outer sheath 604 is configured to engage with an inner contact surface 710 of the lower anchor portion 706. As the locking assembly 610 is being secured to the anchor member 700, the threaded top 802 and the slotted bottom 804 provide a force to the joint 604 a in the axial direction A4 that causes each of the contact members 708 to extend outwards in the radial direction R4.

The burr hole H may have a cylindrical shape that is formed by, for example, a standard clutch perforator. A diameter of the burr hole H may have a substantially similar length as a length of a diameter of the contact members 708 extending about the axial direction A4 in the first position.

The components of the cranial anchoring systems 100, 300, and 600 may be made of a radiolucent material. In another embodiment the components are made of a polymer based material which may have radiolucent or radiopaque materials interspersed in the polymer.

One example of a method for using the cranial anchoring system 300 commences with taking an MRI of a site of interest within a brain and loading it into a surgical navigation system. Based on the information from the MRI, a surgeon may identify a target point in the brain and determine an entry point through the patient's skull S to access the target point. Next, a burr hole H is created in the skull S at the entry point using, for example, but not limited to, a twist drill having a specific geometry. In a preferred aspect, the drill is cone shaped to prep the burr hole H for the attachment of the cranial anchoring system 300. In a further aspect, the diameter of hole H is the size of a standard drill bit, such as 11 millimeters, 14 millimeters, or 18 millimeters. After the hole H is formed, the anchor member 400 is inserted into the hole H, such that the lower anchor portion 406 engages the skull S. The ribs 414 and anchor ribs 430 penetrate the skull S at the edge of the hole H and the tabs 416 contact an inside surface of the skull S, therefore securing the anchor member 400 to the skull S.

After the anchor member 400 has been positioned within the burr hole H, the outer sheath 304 is positioned within the anchor member 400, such that the outer sheath 304 is in rotatable contact with the contact members 408. The contact between the outer sheath 304 and the contact members 408 may further lock the anchor member 400 in place within the hole H by providing a force in the axial direction A3 that is translated by the contact members 408 to provide a force in the radial direction R3. The radial force further secures the ribs 414 and anchor ribs 430 within the edge of the hole H. The locking assembly 310 is positioned within the anchor member 400 to secure the outer sheath 304. Prior to tightening the locking assembly 310, the outer sheath 304 is rotated to a position that may facilitate access to the target point in the brain. Once the outer sheath 304 is in an appropriate position, the locking assembly 310 secures the outer sheath from axial, rotational, and circumferential movement.

The inner sheath 306 is positioned within the outer sheath 304. The position of the inner sheath 306 is adjusted by the height adjustment device 308, and is approximated by the navigation system based off of the MRI, the reference array(s) 312, the angle of the outer sheath 304, the distance the inner sheath 306 extends through the outer sheath 304, or combinations thereof.

The obturator 313 may be used to facilitate the positioning of the inner sheath 306 within the skull S. Once the inner sheath 306 reaches the target point, the obturator 313 is removed and an aspirator pump may be coupled to the upper end of the inner sheath 306 via a flexible tube, thereby allowing the removal of the intracranial fluid and tissue.

Although reference was made to the cranial anchoring system 300 in the above described example for using the cranial anchoring system 300, similar methods may also be employed by the cranial anchoring systems 100 and 600.

The cranial anchoring systems 100, 300, and 600 may be used in a variety of procedures, including, but not limited to, a brain biopsy, an intraventricular surgery, such as a colloid cyst or third ventriculostomy, intracranial hemorrhage clot removal, and for deep brain electrode placement.

All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. The scope of the protected innovation is defined by the attached claims. 

What is claimed:
 1. A cranial anchor system configured to attach to an opening in a cranium, the system comprising: an anchor member that is elongated along a first axis, the anchor member including: a middle anchor portion defining a middle anchor recess that extends about the first axis; and a lower anchor portion extending from the middle anchor portion in a downward direction relative to the middle anchor portion along the first axis, the lower anchor portion including: a plurality of contact members that together define a lower anchor recess, each of the plurality of contact members having: a leg that extends from a bottom of the middle anchor portion, each leg having an angular bend defining an upper and a lower section of the leg, a rib mounted to the leg; and an outer sheath that is elongated along a second axis and defines a first channel, the outer sheath including a joint configured to be at least partially disposed within the middle anchor recess and the lower anchor recess such that the joint is rotatable within the middle anchor recess and the lower anchor recess.
 2. The cranial anchoring system of claim 1, wherein the plurality of contact members are configured to be actuated between a first position and a second position, wherein in the first position a surface of the lower section of the leg extends substantially in the downward direction, and wherein in the second position the surface of the lower section of the leg extends at least partially in a radial direction, wherein the radial direction is substantially perpendicular to the downward direction.
 3. The cranial anchoring system of claim 2, wherein the joint is configured to apply a force to the plurality of contact members to actuate the plurality of contact members between the first position and the second position, and wherein in the second position the rib applies pressure to a wall or edge of the opening to the cranium.
 4. The cranial anchoring system of claim 3, further comprising a locking assembly configured to provide a force to the joint in the downward direction.
 5. The cranial anchoring system of claim 4, wherein the lower anchor portion includes at least one protrusion that extends from an inner surface, and wherein the locking assembly includes a slotted bottom, the slotted bottom having an outer surface that defines at least one slot, wherein each at least one slot is configured to receive each at least one protrusion within, and wherein the anchor member further includes an upper anchor portion extending from the middle anchor portion, the upper anchor portion defining a first threaded region, and wherein the locking assembly further includes a threaded top, the threaded top defines a second threaded region configured to mate with the first threaded region.
 6. The cranial anchoring system of claim 5, wherein the slotted bottom extends from the lower anchor portion to the upper anchor portion when each of the at least one protrusions of the lower anchor portion are within each of the at least one slots of the slotted bottom.
 7. The cranial anchoring system of claim 5, wherein the threaded top is coupled to the slotted bottom, and wherein the locking assembly is sized such that each of the at least one protrusions of the lower anchor portion is received within each of the at least one slots of the slotted bottom prior to the second threaded region of the threaded top being mated with the first threaded region of the upper anchor portion.
 8. The cranial anchoring system of claim 1, wherein the lower section of the leg comprises a planar surface, and wherein the rib is mounted to the lower section of the leg.
 9. The cranial anchoring system of claim 8, wherein the rib includes a sharp edge, wherein the sharp edge extends parallel to the lower section of the leg.
 10. The cranial anchoring system of claim 1, wherein the angular bend forms an obtuse angle between the upper section of the leg and the lower section of the leg.
 11. The cranial anchoring system of claim 1, wherein each of the plurality of contact members is spaced circumferentially about the lower anchor portion, and wherein each rib is mounted to at least one of the upper section of the leg or the lower section of the leg, and wherein each consecutive pair of the plurality of contact members includes a rib mounted on the upper section of the leg and a rib mounted on the lower section of the leg.
 12. A cranial anchor apparatus configured to attach to an opening in a cranium, the anchor apparatus being elongate along a first axis and comprising: a middle anchor portion defining a middle anchor recess that extends about the first axis; and a lower anchor portion coupled to and disposed in a downward direction relative to the middle anchor portion along the first axis, the lower anchor portion including: a plurality of contact members that together define a lower anchor recess, each of the plurality of contact members having: a leg that extends from a bottom of the middle anchor portion, the leg having an angular bend defining an upper and a lower section of the leg, a rib mounted to the leg.
 13. The cranial anchor apparatus of claim 12, wherein each of the plurality of contact members is spaced circumferentially about the lower anchor portion, and wherein each of the plurality of contact members is spaced equidistant from one another.
 14. The cranial anchor apparatus of claim 12, wherein the plurality of contact members are configured to be actuated between a first position and a second position, wherein in the first position a surface of the lower section of the leg extends substantially in the downward direction, and wherein in the second position the surface of the lower section of the leg extends at least partially in a radial direction, wherein the radial direction is substantially perpendicular to the downward direction.
 15. The cranial anchor apparatus of claim 14, wherein when the cranial anchor apparatus is attached to the opening in the cranium and the plurality of contact members are in the second position the rib applies a pressure to a wall or edge of the opening to the cranium.
 16. The cranial anchor apparatus of claim 12, wherein the lower anchor portion further includes a support ring disposed about the first axis and below at least a portion of each of the plurality of contact members. 